rmtest23.c

快速傅立叶变换程序代码,学信号的同学,可要注意了

/*
  RMtest.c  April 1997 DJCM (c)

  demonstrates a few uses of RM.c, which 
  contains routines for creating RM trellises and Hamming too,
  and for doing belief propagation on them

  the trellis goes from l=0 to N, with 
  the number of emitted bits being N. 
  from 0 to 1, bit 1 is emitted.
  from N-1 to N, bit N is emitted. 
*/

#include "./ansi/r.h"
#include "./ansi/rand2.h"
#include "./ansi/mynr.h"
#include "./ansi/cmatrix.h"
#include "./RM.h" 

void   main ( int , char ** ) ;

/*
        MAIN
                     */
void main ( int argc, char *argv[] )
{
  linear_trellis t ;
  int verbosity = 1 ; 
  int type = 3 ; /* type 1 makes hamming and RM codes; type 0 makes Gallager */
  double fn = 0.1 ; 
  int i ; 
  int flipone = 1 ; 
  int testword , testmax = 65 , tmpi , s ; 
  
  printf ( "first, let's show a load of trellises\n");
  printf ( "============================= M =  23\n");
  make_linear_trellis ( &t , 12 , 2 , verbosity ) ;
  printf ( "let's check a few codewords\n");
  pause_for_return();
  for ( testword = 0 ; testword <= testmax ; testword ++ ) {
    tmpi = testword ; 
    for (  i= 1; i<= t.N ; i++ ) {
      t.xo[i] = tmpi % 2 ; 
      tmpi /= 2 ; 
      printf ( "%d" , ( t.xo[i]? 1:0 ) ) ; 
    }
    s = lt_syndrome ( &t )  ;
    printf ( " %3o syndrome is %3o\n" , testword , s ) ; 

  }
  free_linear_trellis ( &t ) ;
  printf ( "============================= M =  24\n");
  make_linear_trellis ( &t , 24 ,type, verbosity ) ;
  free_linear_trellis ( &t ) ;
  pause_for_return();
  printf ( "============================= shortened hamming\n");
  make_linear_trellis ( &t , 12 , 2 , verbosity ) ;
  pause_for_return();
  printf ( "Now see fb happening, when the received vector looks like 0,0,0,0,0\n");
  /* invent a q vector */
  for ( i= 1; i<= t.N ; i++ ) {
    t.q[i][0] = 1.0 - fn ; t.q[i][1] = fn ;
  }
  lt_fb ( &t ) ; 
  pause_for_return();
  printf ( "Do it again to check that there is no problem\n");
  pause_for_return();
  lt_fb ( &t ) ; 
  pause_for_return();
  if ( flipone ) { 
    printf ( "Now the received vector is (1,0,0,0,0..) \n");
    t.q[1][0] = fn ; t.q[1][1] =  1.0 - fn ; 
    lt_fb ( &t ) ; 
    pause_for_return();
  }
  printf ( "Now see fb happening at a sequence of different noise levels\n");
  pause_for_return();
  for ( fn = 0.04 ; fn <= 0.43 ; fn += 0.04 ) {
    printf ("fn = %9.5g ========== \n",fn) ; 
    for ( i= 1; i<= t.N ; i++ ) {
      t.q[i][0] = 1.0 - fn ; t.q[i][1] = fn ;
    }
    if ( flipone ) { t.q[1][0] = fn ; t.q[1][1] =  1.0 - fn ; }
    lt_fb ( &t ) ; 
    pause_for_return();
  }



}

/*
<!-- hhmts start -->
Last modified: Tue Nov 21 20:01:32 1995
<!-- hhmts end -->
*/